In accordance with the National Institutes of Health's and the National Institute of Nursing Research's missions to understand the effect of disease symptoms and their effect on disability progression, the applicant proposes to study the symptoms, physical activity, and quality of life before and after cardiac ^synchronization therapy in patients with heart failure. The specific aim of the study is to determine if changes in physical function translate into increased daily physical activity in heart failure patients who undergo implantation of cardiac resynchronization therapy. The study is of a pre-/post - quasi-experimental design. Sixty subjects from two enrollment sites will complete a six-minute walk test to examine physical function, the Daily Activity Questionnaire in Heart Failure to assess physical activity patterns, and the Chronic Heart Failure Questionnaire to assess heart failure symptoms before and three-months after implant of cardiac resynchronization therapy. Physical activity patterns before and after cardiac resynchronization therapy have not been documented. The long-term goals of the applicant are to address objectives from Healthy People 2010 in promoting optimum health via physical activity and to utilize upcoming exercise recommendations from the trial, HF-Action, sponsored by the National Heart, Lung, and Blood Institute to determine implications for those with cardiac resynchronization therapy. There are 5 million Americans afflicted with heart failure and over 550,000 new cases diagnosed eachyear. The number of persons receiving the new treatment of cardiac resynchronization therapy also continues to grow. Data have shownthat cardiac resynchronization therapy improves symptoms and physical function, but there has been no translation of this effect to daily physical activity levels. Thus, the applicant proposes her study to address this knowledge gap with the long-term goal to provide exercise prescription specific to this population for continued improvement in physical activity levels, better quality of life, attenuated heart failure symptoms, and prevention of debilitating secondary conditions.